Methods of treating autoimmune diseases with Dll4 antagonists

ABSTRACT

The present invention provides methods of treating a disease or disorder, in which increasing the number of regulatory T cell (Treg) is beneficial, by administering to a subject suffering from such a disease or disorder a therapeutically effective amount of Dll4 antagonists that block Dll4-Notch signal pathways, thereby increasing the number of Treg. Diseases or disorders treatable by the methods of the invention include autoimmune diseases or disorders, such as multiple sclerosis (MS), diabetes, and the like. Suitable Dll4 antagonists for the invention include antibodies or antibody fragments that specifically bind Dll4 and block Dll4-Notch interactions, the extracellular domain of Dll4, and the like. The invention also provides methods of preventing an occurrence or recurrence of such diseases or disorders in a subject predisposed or susceptible to developing such diseases or disorders. Furthermore, the methods of the invention are useful in preventing or treating organ transplant rejections or graft-versus-host disease.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) of U.S.provisional application Nos. 61/299,801 filed Jan. 29, 2010; 61/361,687filed Jul. 6, 2010; and 61/388,697 filed Oct. 1, 2010, all of which areherein specifically incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to methods of treating a disease, disorder, orcondition, in which increasing the number of regulatory T cells (Tregcells or Tregs) is beneficial, using delta-like ligand 4 (Dll4)antagonists. More specifically, the methods of the invention can treatvarious autoimmune diseases, such as multiple sclerosis and diabetes, aswell as organ transplant rejections and graft-versus-host diseases(GVHD) by blocking the binding of Dll4 to a Notch receptor with Dll4antagonists, thereby increasing the number of Tregs. The inventionfurther relates to methods of preventing such diseases or disorders fromoccurring or recurring in a subject who is predisposed or susceptible tothe diseases or disorders.

2. Description of Related Art

Interactions between Notch receptors and their ligands represent anevolutionarily conserved pathway important not only for cell fatedecisions but also in regulating lineage decisions in hematopoiesis andin the developing thymus (Artavanis-Tsakonas et al. 1999, Science284:770-776; Skokos et al. 2007; J Exp Med 204:1525-1531; and Amsen etal. 2004, Cell 117:515-526). It has been recently shown that Dll4-Notch1inhibition leads to a complete block in T cell development accompaniedby ectopic appearance of B cells and an expansion of dendritic cells(DC) that can arise from Pro-T cell to DC fate conversion within thethymus (Hozumi et al. 2008, J Exp Med 205(11):2507-2513; Koch et al.2008, J Exp Med 205(11):2515-2523; and Feyerabend et al. 2009, Immunity30:1-13). Thus, there is accumulating evidence that Notch signaling iscritical for the determination of cell fate decision from hematopoieticprogenitor cells. Furthermore, a feedback control of regulatory T cell(Treg) homeostasis by DCs in vivo has been shown (Darrasse-Jèze et al.2009, J Exp Med 206(9):1853-1862). However, the role of Notch signalingin controlling the origin and the development of DCs and consequentlyTreg homeostasis is still unknown. This is a question clinicallyimportant because identifying new methods of inducing Treg expansioncould be used as a treatment for autoimmunity diseases and disorders.

The nucleic acid and amino acid sequences of human Dll4 (hDll4) areshown in SEQ ID NOS:1 and 2, respectively. Dll4 antagonists and theiruses are disclosed in WO 2007/143689, WO 2007/070671, WO 2008/076379, WO2008/042236, and WO/2008/019144.

BRIEF SUMMARY OF THE INVENTION

The present invention is based in part on the observation by the presentinventor that an antibody, which specifically binds Dll4 and blocks Dll4binding to Notch receptors, is able to fully prevent a progression ofExperimental Autoimmune Encephalomyelitis (EAE) in mice, an animal modelfor human multiple sclerosis, while a control antibody does not preventEAE. Furthermore, the present inventor has discovered that this effectof anti-Dll4 antibody is associated with the increased number of Tregcells. In addition, it has been further observed that an anti-Dll4antibody prevents an increase in blood glucose level and preserves thenumber and morphology of pancreatic islets in NOD/ShiLtJ mice, an animalmodel for type 1 diabetes, and such effects are, at least in part,mediated by the expansion of Tregs.

Thus, in a first aspect, the invention features a method of increasingthe number of Treg cells, comprising administering an effective amountof a Dll4 antagonist to a subject in need thereof, wherein the Dll4antagonist blocks the interaction between Dll4 and a Notch receptor andthe number of Treg cells is increased.

In a second aspect, the invention features a method of treating orameliorating a disease, disorder, or condition in which increasing thenumber of Treg cells is beneficial, comprising administering atherapeutically effective amount of a Dll4 antagonist to a subject inneed thereof. The disease or disorder treatable by the methods of theinvention is any disease, disorder, or condition which is benefited,i.e., improved, ameliorated, inhibited or prevented by removal,inhibition or reduction of Dll4 activity, thereby increasing the numberof Treg cells in the treated subject. Such diseases, disorders, orconditions include, but are not limited to, a variety of autoimmunediseases, such as multiple sclerosis, diabetes mellitus type 1 and type2, rheumatoid arthritis, Crohn's disease, Goodpasture's syndrome,Graves' disease, Guillain-Barré syndrome (GBS), Hashimoto's disease,idiopathic thrombocytopenic purpura, irritable bowel syndrome, lupuserythematosus, mixed connective tissue disease, myasthenia gravis,narcolepsy, pemphigus vulgaris, pernicious anemia, polymyositis, primarybiliary cirrhosis, Sjögren's syndrome, ulcerative colitis, vasculitis,Wegener's granulomatosis, and the like, as well as organ transplantrejections and GVHD.

In one embodiment, the Dll4 antagonist to be used in the methods of theinvention is a Dll4 antibody or fragment thereof (“anti-Dll4 Ab” or“Dll4 Ab”) that specifically binds Dll4 with high affinity and blocksthe binding of Dll4 to the Notch receptors and/or blocks the Dll4-Notchsignal pathways. The antibody may be polyclonal, monoclonal (mAb),chimeric, humanized, or a wholly human antibody or fragment thereof. Theantibody fragment may be a single chain antibody, an Fab, or an (Fab′)₂.

In one embodiment, the Dll4 Ab or antigen-binding fragment thereof bindsan epitope within the N-terminal domain (residues S27-R172), or theDelta/Serrate/Lag-2 (DSL) domain (residues V173-C217), or theN-terminal-DSL domain (residues S27-C217), of hDll4 (SEQ ID NO:2). Inanother embodiment, the Dll4 Ab or antigen-binding fragment thereofbinds an epitope within one of the EGF domains, i.e., at about aminoacid residues Q218-N251 (domain 1), E252-D282 (domain 2), D284-E322(domain 3), E324-E360 (domain 4), S362-E400 (domain 5), K402-E438(domain 6), H440-E476 (domain 7), or S480-E518 (domain 8), of hDll4 (SEQID NO:2). In some embodiments, the antibody or antibody fragment maybind a conformational epitope involving more than one of the epitopesenumerated above. The Dll4 Ab or fragment thereof to be used in themethods of the invention is capable of binding human Dll4 with highaffinity and has an equilibrium dissociation constant (K_(D)) of about 1nM or less, about 500 pM or less, about 300 pM or less, about 200 pM orless, about 100 pM or less, or about 50 pM or less, as measured bysurface plasmon resonance.

In one embodiment, the Dll4 Ab or fragment thereof comprises a heavychain variable region (HCVR) comprising three heavy chaincomplementarity determining regions, HCDR1, HCDR2 and HCDR3, having theamino acid sequences of SEQ ID NOS: 22, 24 and 26, respectively. Inanother embodiment, the antibody or fragment thereof comprises a lightchain variable region (LDVR) comprising three light chaincomplementarity determining regions, LCDR1, LCDR2 and LCDR3, having theamino acid sequences of SEQ ID NOS:30, 32 and 34, respectively. Inanother embodiment, the Dll4 Ab or fragment thereof comprises the heavyand light chain CDR sequences comprising a CDR sequence combination ofSEQ ID NOS:22, 24, 26, 30, 32 and 34. In yet another embodiment, theDll4 Ab comprises a HCVR comprising the amino acid sequence of SEQ IDNO:20 or 116, or a LCVR comprising the amino acid sequence of SEQ IDNO:28 or 118. In yet another embodiment, the Dll4 Ab comprises aHCVR/LCVR combination of SEQ ID NO:20/28 (REGN281) or 116/118 (REGN421).

In certain embodiments, the Dll4 Ab comprises a heavy chainCDR1/CDR2/CDR3 combination and a light chain CDR1/CDR2/CDR3 combinationselected from: SEQ ID NO:6/8/10 and SEQ ID NO:14/16/18, respectively;SEQ ID NO:38/40/42 and SEQ ID NO:46/48/50, respectively; SEQ IDNO:54/56/58 and SEQ ID NO:62/64/66, respectively; SEQ ID NO:70/72/74 andSEQ ID NO:78/80/82, respectively; SEQ ID NO:86/88/90 and SEQ IDNO:94/96/98, respectively; and SEQ ID NO:102/104/106 and SEQ IDNO:110/112/114, respectively. In another embodiment, the Dll4 Abcomprises a HCVR comprising the amino acid sequence of SEQ ID NO:4, 36,52, 68, 84, or 100, or a LCVR comprising the amino acid sequence of SEQID NO:12, 44, 60, 76, 92, or 108. In yet another embodiment, the Dll4 Abcomprises a HCVR/LCVR combination selected from: SEQ ID NO:4/12(REGN279); SEQ ID NO:36/44 (REGN290); SEQ ID NO:52/60 (REGN306); SEQ IDNO:68/76 (REGN309); SEQ ID NO:84/92 (REGN310); and SEQ ID NO:100/108(REGN289).

The nucleotide sequences encoding the amino acid sequences of SEQ IDNOS:4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38,40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74,76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108,110, 112, 114, 116 and 118, are shown as SEQ ID NOS:3, 5, 7, 9, 11, 13,15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49,51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85,87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115 and117, respectively.

In another embodiment, the Dll4 antagonist usable in the methods of theinvention is a fusion protein comprising at least one soluble Notchreceptor or fragment thereof capable of binding Dll4, fused to amultimerizing component. In one embodiment, the soluble Notch receptoris human Notch1 or Notch4. In another embodiment, the Dll4 antagonist ofthe invention is a modified Dll4 protein that is capable of binding theNotch receptor(s) but such binding does not result in activation of thereceptor(s). In certain embodiments, the Dll4 antagonist of theinvention is a fusion protein comprising the extracellular domain ofDll4 or a fragment thereof fused to a multimerizing component, such asan immunoglobulin domain, for example, an Fc domain of a human IgG. Incertain embodiments, the Dll4 antagonists include small molecules andother agents that can block Dll4-Notch interactions.

In a third aspect, the invention features a method of preventing orreducing an occurrence or recurrence of an autoimmune disease ordisorder, as described above, in a subject who is predisposed orsusceptible to developing the disease or disorder, comprisingadministering to the subject a prophylactically effective amount of aDll4 antagonist. In a related embodiment, the invention further featuresa method of preventing or reducing a possibility of an organ transplantrejection or GVHD in a transplant recipient, comprising administering aprophylactically effective amount of a Dll4 antagonist to the recipientbefore and/or after the transplantation.

In a fourth aspect, the invention features a method of preventing,treating or ameliorating an autoimmune disease or disorder, or an organtransplant rejection, comprising administering to a subject in needthereof an effective amount of a Dll4 antagonist in combination with anadditional therapeutic agent, for example, an immunosuppressive agent orimmunosuppressant, anti-inflammatory agent, analgesic agent, bloodglucose lowering agent (e.g., insulin, insulin analogues, and the like),many of which may have overlapping therapeutic effects of one another.Suitable immunosuppressants to be used in combination with the Dll4antagonist include, but are not limited to, glucocorticoids,cyclosporin, methotrexate, interferon β (IFN-β), tacrolimus, sirolimus,azathioprine, mercaptopurine, opioids, mycophenolate, TNF-bindingproteins, such as infliximab, eternacept, adalimumab, and the like,cytotoxic antibiotics, such as dactinomycin, anthracyclines, mitomycinC, bleomycin, mithramycin, and the like, antibodies targeting immunecells, such as anti-CD20 antibodies, anti-CD3 antibodies, and the like.Suitable anti-inflammatory agents and/or analgesics for combinationtherapies with anti-Dll4 antagonists include, corticosteroids,non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin,ibuprofen, naproxen and the like, TNF-α antagonists, IL-1 antagonists,IL-6 antagonists, acetaminophen, morphinomimetics, and the like.

In a fifth aspect, the invention features a pharmaceutical compositioncomprising a Dll4 antagonist, at least one additional therapeutic agent,and a pharmaceutically acceptable carrier. In one embodiment, the Dll4antagonist is a Dll4 Ab or fragment thereof that specifically binds toDll4 with high affinity and neutralizes Dll4 activities, and at leastone additional therapeutic agent is any of the immunosuppressants,anti-inflammatory agents, analgesics, glucose lowering agents, and thelike, described above.

In a sixth aspect, the invention features a kit comprising a containercomprising the pharmaceutical composition of the present invention, anda package insert with an instruction for use. In one embodiment, a kitmay comprise a container comprising therein an antibody or fragmentthereof that specifically binds hDll4, another container comprisingtherein at least one additional therapeutic agent described above.

Other objects and advantages will become apparent from a review of theensuing detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A-1B show the effects of Dll4 blockade on the development of Tcells and B cells. Mice were injected with anti-Dll4 antibody (REGN577)or control human Fc fragment (hFc). Fourteen days later, thymi wereharvested and T-cell and B-cell subsets were evaluated by flowcytometry. FIG. 1A: Dot plots show the number of CD4⁻CD8⁻ (doublenegative thymic precursors or “DN”), CD4⁺CD8⁺ (double positive thymicprecursors or “DP”), CD4⁺ or CD8⁺ (single positive thymic precursors or“SP”), and DN/CD44⁺CD25⁻ (thymic precursors at the DN1 stage) T cells.The numbers in the dot plots represent percentages (mean±SEM) of T cellsubpopulations among the total thymic cells. FIG. 1B: Histograms showthe percentage (mean±SD) of B cells (B220⁺) among DN1 cells (i.e., gatedon CD4⁻CD8⁻CD44⁺CD25⁻).

FIG. 2A-2B show the effects of Dll4 blockade on B cell developmentalstages in the bone marrow (FIG. 2A) and on B cell homeostasis in thespleen (FIG. 2B). The numbers in the dot plots represent percentages(mean±SEM) of B cell subsets among the total cells in bone marrow or inspleen. GC: Germinal center B cells; T1 and T2: B cell subsets; M:Marginal B cells; and Fo: Follicular B cells.

FIG. 3A-3D show the effects of Dll4 blockade on dendritic cell (DC)development. FIG. 3A: Dot plots show the expansion of conventional DCs(“cDCs”; B220⁻CD11C⁺) and plasmacytoid DCs (“pDCs”; PDCA1⁺B220⁺CD11C⁺)in the thymus upon anti-Dll4 Ab treatment. Numbers in dot plotsrepresent average percentages (mean±SEM) of DCs among total cells at day14. FIG. 3B: The bar graphs show the kinetics of cDC and pDC expansionin the thymus of Dll4 Ab-treated mice (▪) and hFc-control treated mice(□). FIG. 3C: Dot plots show the effects of Dll4 Ab on pre-DCs(MHCII^(lo)CD11c^(int)CD135⁺Sirp-α^(int)) and late pre-DCs(MHCII^(lo)CD11c^(int)) in the thymus. Numbers in dot plots representaverage percentages (mean±SEM) of pre-DCs among total cells at day 14.FIG. 3D: Dot plots show the presence of MHCII^(lo)CD11c^(int) DCs in theDN1 (CD4⁻CD8⁻CD44⁺CD25⁻) pro-T cell population in the thymus of micetreated with Dll4 Ab, but not in the thymus of mice treated with hFccontrol Ab. Numbers in dot plots represent average number (mean±SEM) ofMHCII^(lo)CD11c^(int) DCs among DN1 pro-T cell population at day 3.

FIG. 4 shows the effect of Dll4 blockade on the development ofintra-thymic alternative DC lineage into immature DCs (imDCs)originating from a common T/DC DN1 progenitor. DN1 CD45.1⁺Lin⁻ sortedcells were intra-thymically transferred into CD45.2⁺ host mice treatedwith Dll4 Ab (▪) or hFc control Ab (□).

FIG. 5 shows the effect of Dll4 blockage on serum levels of CSF-1(M-CSF), a key cytokine involved in DC development. Serum CSF-1 levelsof mice untreated (

), or treated with isotype control Ab (□), or Dll4 Ab (▪) were measuredby enzyme-linked immunosorbent assay (ELISA).

FIG. 6 shows the effects of the genetic Dll4 deletion, upon tamoxifentreatment, on B cell and DC homeostasis in DLL4COIN mice containing atamoxifen-inducible Cre recombinase construct, CreERT2. Numbers in dotplots represent average percentages (mean±SEM) of B cells and both pDCsand cDCs among total cells in the thymus.

FIG. 7A-7C show the effects of Dll4 blockade/deletion on Treghomeostasis. FIG. 7A: Dot plots show an expansion of Tregs within thethymus of mice treated with Dll4-Ab for two weeks, compared to micetreated with hFc control Ab. Numbers in dot plots represent averagepercentages (mean±SEM) of Tregs among CD3⁺CD4⁺ T cells in the thymus.FIG. 7B: Bar graphs show the kinetics of Treg development in thymus(upper panel) and spleen (lower panel), respectively, of the micetreated with Dll4 Ab (▪) and hFc control Ab (□). FIG. 7C: Dot plots showan expansion of Tregs within the thymus of DLL4COIN mice treated withtamoxifen (TAM), compared to control DLL4COIN treated with corn oilcontrol. Numbers in dot plots represent average percentages (mean±SEM)of Tregs among CD3⁺CD4⁺ T cells in the thymus.

FIG. 8A-8B show the effects of Dll4 blockade on DC (FIG. 8A) and Treghomeostasis (FIG. 8B) in the thymus of mice expressing human Dll4(hDll4) observed at days 7 and 14 after Dll4-Ab (REGN421) treatment (1mg/kg or 5 mg/kg) or hFc treatment (5 mg/kg), twice per week for 2 weeksand at day 28 after the cessation of treatment. Numbers in dot plotsrepresent average percentages (mean±SEM) of pDCs and cDCs (FIG. 8A) orTregs (FIG. 8B) among total cells in the thymus.

FIG. 9A-9B show the effects of Dll4 blockade in Experimental AutoimmuneEncephalomyelitis (EAE) mouse model. FIG. 9A: The graph shows EAEdisease incidence rates (%) per treatment group. FIG. 9B: The graphshows the development of EAE based on average disease scores. Treatmentwas with anti-Dll4 Ab (REGN577) pre-induction (▾); isotype control Abpre-induction (♦); REGN577 post-induction (▴); or anti-VLA-4 Ab (PS/2)pre-induction (▪).

FIG. 10 shows the effects of Dll4 blockade on IL-17 and IFN-γ productionin the lymph nodes of EAE mice. The levels of IL-17 (left panel) andIFN-γ (right panel) in the lymph nodes of EAE mice treated with Dll4 Ab(▪) or hFc control Ab (□) were measured on days 12 and 18 by ELISA.

FIG. 11A-11E show the effects of Dll4 Ab in a NOD mouse diabetic model.FIG. 11A shows the % diabetes incidence (two consecutive readings ofblood glucose level higher than 250 mg/dL) among the mice that receivedeither hFC control Ab (•) or anti-Dll4 Ab (REGN577) (▪) at 9 weeks ofage. The % diabetes incidence of five mice that had been treated withthe Dll4 Ab and subsequently injected with PC61 Ab at 20 weeks is alsoshown (♦). PC61 Ab is an anti-CD25 antibody and depletes Treg cells.FIG. 11B shows the measurement by ELISA of anti-insulin autoantibody (□)and anti-glutamic acid decarboxylase 65 (GAD65) autoantibody (▪)productions in NOD mice treated with Dll4 Ab or hFc control, compared tountreated wild type (WT) mice. FIG. 11C shows pancreatic sectionsstained with Hematoxylin and Eosin (H&E) of NOD mice treated with Dll4Ab (left panel) or hFc control (right panel). Black arrows indicateindividual pancreatic islets and white arrow indicates infiltratingcells within the islet (right panel). FIG. 11D shows the number ofpancreatic islets (left panel) or % of infiltrated pancreatic islets(right panel) in the pancreas of hFc control-treated (□) or Dll4Ab-treated (▪) mice. FIG. 11E shows the changes in blood glucose levelin mice treated, at the onset of the disease, with Dll4 Ab (•) or hFccontrol (□), over 42 days after the treatment.

DETAILED DESCRIPTION

Before the present methods are described, it is to be understood thatthis invention is not limited to particular methods, and experimentalconditions described, as such methods and conditions may vary. It isalso to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting, since the scope of the present invention will be limitedonly by the appended claims.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural references unless the contextclearly dictates otherwise. Thus for example, a reference to “a method”includes one or more methods, and/or steps of the type described hereinand/or which will become apparent to those persons skilled in the artupon reading this disclosure.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present invention, the preferred methodsand materials are now described. All publications mentioned herein areincorporated herein by reference in their entirety.

Definitions

The term “Dll4 antagonists”, as used herein, include antibodies to Dll4and fragments thereof capable of blocking the binding of Dll4 to a Notchreceptor (such as Notch1 and Notch4) and/or blocking Dll4-Notch signalpathways (see, for example, WO 2008/076379), fusion proteins comprisingthe extracellular domain of Dll4 fused to a multimerizing component, orfragments thereof (see for example, US patent publication nos.2006/0134121 and 2008/0107648), peptides and peptibodies (see, forexample, U.S. Pat. No. 7,138,370), and the like, which block theinteraction between Dll4 and a Notch receptor. Thus, in certainembodiments, the term also encompasses antagonists, such as smallmolecules, antibodies or antigen-binding fragments thereof, and thelike, that specifically bind Notch receptors (e.g., anti-Notch1antibodies, anti-Notch4 antibodies, etc.) and block Dll4-Notch signalpathways.

The term “antibody”, as used herein, is intended to refer toimmunoglobulin molecules comprised of four polypeptide chains, two heavy(H) chains and two light (L) chains inter-connected by disulfide bonds.Each heavy chain is comprised of a heavy chain variable region(abbreviated herein as HCVR or V_(H)) and a heavy chain constant region(C_(H)). The heavy chain constant region is comprised of three domains,C_(H)1, C_(H)2 and C_(H)3. Each light chain is comprised of a lightchain variable region (abbreviated herein as LCVR or V_(L)) and a lightchain constant region. The light chain constant region is comprised ofone domain, C_(L). The V_(H) and V_(L) regions can be further subdividedinto regions of hypervariability, termed complementarity determiningregions (CDR), interspersed with regions that are more conserved, termedframework regions (FR). Each V_(H) and V_(L) is composed of three CDRsand four FRs, arranged from amino-terminus to carboxy-terminus in thefollowing order: FR1, CDR1, FR2, CDR2, FR3, CDR3, and FR4.

Methods and techniques for identifying CDRs within HCVR and LCVR aminoacid sequences are known in the art and can be applied to identify CDRswithin the specified HCVR and/or LCVR amino acid sequences disclosedherein. Conventions that can be used to identify the boundaries of CDRsinclude the Kabat definition, the Chothia definition, and the AbMdefinition. In general terms, the Kabat definition is based on sequencevariability, the Chothia definition is based on the location of thestructural loop regions, and the AbM definition is a compromise betweenthe Kabat and Chothia approaches. See, e.g., Kabat, “Sequences ofProteins of Immunological Interest,” National Institutes of Health,Bethesda, Md. (1991); Al-Lazikani et al., J. Mol. Biol. 273:927-948(1997); and Martin et al., Proc. Natl. Acad. Sci. USA 86:9268-9272(1989). Public databases are also available for identifying CDRsequences within an antibody

Substitution of one or more CDR residues or omission of one or more CDRsis also possible. Antibodies have been described in the scientificliterature in which one or two CDRs can be dispensed with for binding.Padlan et al. (1995 FASEB J. 9:133-139) analyzed the contact regionsbetween antibodies and their antigens, based on published crystalstructures, and concluded that only about one fifth to one third of CDRresidues actually contact the antigen. Padlan also found many antibodiesin which one or two CDRs had no amino acids in contact with an antigen(see also, Vajdos et al. 2002 J Mol Biol 320:415-428).

CDR residues not contacting antigen can be identified based on previousstudies (for example, residues H60-H65 in CDRH2 are often not required),from regions of Kabat CDRs lying outside Chothia CDRs, by molecularmodeling and/or empirically. If a CDR or residue(s) thereof is omitted,it is usually substituted with an amino acid occupying the correspondingposition in another human antibody sequence or a consensus of suchsequences. Positions for substitution within CDRs and amino acids tosubstitute can also be selected empirically. Empirical substitutions canbe conservative or non-conservative substitutions.

The term “antibody” also encompasses antibodies having a modifiedglycosylation pattern. In some applications, modification to removeundesirable glycosylation sites may be useful, or e.g., removal of afucose moiety to increase antibody dependent cellular cytotoxicity(ADCC) function (see Shield et al. (2002) JBC 277:26733). In otherapplications, removal of N-glycosylation site may reduce undesirableimmune reactions against the therapeutic antibodies, or increaseaffinities of the antibodies. In yet other applications, modification ofgalactosylation can be made in order to modify complement dependentcytotoxicity (CDC).

The term “antigen-binding fragment” of an antibody (or simply “antibodyfragment”), as used herein, refers to one or more fragments of anantibody that retain the ability to specifically bind to hDll4, or anyother intended target proteins. An antibody fragment may include a Fabfragment, a F(ab′)₂ fragment, a Fd fragment, a Fv fragment, asingle-chain Fv (scFv) molecule, a dAb fragment, minimal recognitionunits consisting of the amino acid residues that mimic the hypervariableregion of an antibody (e.g., a fragment containing a CDR, or an isolatedCDR). Other engineered molecules, such as diabodies, triabodies,tetrabodies and minibodies, are also encompassed within the expression“antigen-binding fragment”, as used herein. In certain embodiments,antibody or antibody fragments of the invention may be conjugated to atherapeutic moiety (“immunoconjugate”), such as a cytotoxin, achemotherapeutic drug, an immunosuppressant or a radioisotope.

An antigen-binding fragment of an antibody will typically comprise atleast one variable domain. The variable domain may be of any size oramino acid composition and will generally comprise at least one CDRwhich is adjacent to or in frame with one or more framework sequences.In antigen-binding fragments having a V_(H) domain associated with aV_(L) domain, the V_(H) and V_(L) domains may be situated relative toone another in any suitable arrangement. For example, the variableregion may be dimeric and contain V_(H)-V_(H), V_(H)-V_(L) orV_(L)-V_(L) dimers. Alternatively, the antigen-binding fragment of anantibody may contain a monomeric V_(H) or V_(L) domain.

In certain embodiments, an antigen-binding fragment of an antibody maycontain at least one variable domain covalently linked to at least oneconstant domain. Non-limiting, exemplary configurations of variable andconstant domains that may be found within an antigen-binding fragment ofan antibody of the present invention include: (i) V_(H)-C_(H)1; (ii)V_(H)-C_(H)2; (iii) V_(H)-C_(H)3; (iv) V_(H)-C_(H)1-C_(H)2; (v)V_(H)-C_(H)1-C_(H)2-C_(H)3; (vi) V_(H)-C_(H)2-C_(H)3; (vii) V_(H)-C_(L);(viii) V_(L)-C_(H)1; (ix) V_(L)-C_(H)2; (x) V_(L)-C_(H)3; (xi)V_(L)-C_(H)1-C_(H)2; (xii) V_(L)-C_(H)1-C_(H)2-C_(H)3; (xiii)V_(L)-C_(H)2-C_(H)3; and (xiv) V_(L)-C_(L). In any configuration ofvariable and constant domains, including any of the exemplaryconfigurations listed above, the variable and constant domains may beeither directly linked to one another or may be linked by a full orpartial hinge or linker region. A hinge region may consist of at least 2(e.g., 5, 10, 15, 20, 40, 60 or more) amino acids which result in aflexible or semi-flexible linkage between adjacent variable and/orconstant domains in a single polypeptide molecule. Moreover, anantigen-binding fragment of an antibody of the present invention maycomprise a homo-dimer or hetero-dimer (or other multimer) of any of thevariable and constant domain configurations listed above in non-covalentassociation with one another and/or with one or more monomeric V_(H) orV_(L) domain (e.g., by disulfide bond(s)).

As with full antibody molecules, antigen-binding fragments may bemonospecific or multispecific (e.g., bispecific). A multispecificantigen-binding fragment of an antibody will typically comprise at leasttwo different variable domains, wherein each variable domain is capableof specifically binding to a separate antigen or to a different epitopeon the same antigen. Any multispecific antibody format may be adaptedfor use in the context of an antigen-binding fragment of an antibody ofthe present invention using routine techniques available in the art.

The term “human antibody”, as used herein, is intended to includeantibodies having variable and constant regions derived from humangermline immunoglobulin sequences. The human mAbs of the invention mayinclude amino acid residues not encoded by human germline immunoglobulinsequences (e.g., mutations introduced by random or site-specificmutagenesis in vitro or by somatic mutation in vivo), for example in theCDRs and in particular CDR3. However, the term “human antibody”, as usedherein, is not intended to include mAbs in which CDR sequences derivedfrom the germline of another mammalian species (e.g., mouse), have beengrafted onto human FR sequences.

The fully-human anti-Dll4 antibodies disclosed herein may comprise oneor more amino acid substitutions, insertions and/or deletions in theframework and/or CDR regions of the heavy and light chain variabledomains as compared to the corresponding germline sequences. Suchmutations can be readily ascertained by comparing the amino acidsequences disclosed herein to germline sequences available from, forexample, public antibody sequence databases. The present inventionincludes antibodies, and antigen-binding fragments thereof, which arederived from any of the amino acid sequences disclosed herein, whereinone or more amino acids within one or more framework and/or CDR regionsare mutated to the corresponding residue(s) of the germline sequencefrom which the antibody was derived, or to the corresponding residue(s)of another human germline sequence, or to a conservative amino acidsubstitution of the corresponding germline residues(s) (such sequencechanges are referred to herein collectively as “germline mutations”). Aperson of ordinary skill in the art, starting with the heavy and lightchain variable region sequences disclosed herein, can easily producenumerous antibodies and antigen-binding fragments which comprise one ormore individual germline back-mutations or combinations thereof. Incertain embodiments, all of the framework and/or CDR residues within theV_(H) and/or V_(L) domains are mutated back to the residues found in theoriginal germline sequence from which the antibody was derived. In otherembodiments, only certain residues are mutated back to the originalgermline sequence, e.g., only the mutated residues found within thefirst 8 amino acids of FR1 or within the last 8 amino acids of FR4, oronly the mutated residues found within CDR1, CDR2 or CDR3. In otherembodiments, one or more of the framework and/or CDR residue(s) aremutated to the corresponding residue(s) of a different germline sequence(i.e., a germline sequence that is different from the germline sequencefrom which the antibody was originally derived). Furthermore, theantibodies of the present invention may contain any combination of twoor more germline mutations within the framework and/or CDR regions,e.g., wherein certain individual residues are mutated to thecorresponding residues of a particular germline sequence while certainother residues that differ from the original germline sequence aremaintained or are mutated to the corresponding residue of a differentgermline sequence. Once obtained, antibodies and antigen-bindingfragments that contain one or more germline mutations can be easilytested for one or more desired property such as, improved bindingspecificity, increased binding affinity, improved or enhancedantagonistic or agonistic biological properties (as the case may be),reduced immunogenicity, etc. Antibodies and antigen-binding fragmentsobtained in this general manner are encompassed within the presentinvention.

The present invention also includes anti-Dll4 antibodies comprisingvariants of any of the HCVR, LCVR, and/or CDR amino acid sequencesdisclosed herein having one or more conservative substitutions. Forexample, the present invention includes anti-Dll4 antibodies havingHCVR, LCVR, and/or CDR amino acid sequences with, e.g., 10 or fewer, 8or fewer, 6 or fewer, 4 or fewer, 2 or 1, conservative amino acidsubstitution(s) relative to any of the HCVR, LCVR, and/or CDR amino acidsequences disclosed herein. In one embodiment, a HCVR comprises theamino acid sequence of SEQ ID NO:116 with 10 or fewer conservative aminoacid substitutions therein. In another embodiment, a HCVR comprises theamino acid sequence of SEQ ID NO:116 with 8 or fewer conservative aminoacid substitutions therein. In another embodiment, a HCVR comprises theamino acid sequence of SEQ ID NO:116 with 6 or fewer conservative aminoacid substitutions therein. In another embodiment, a HCVR comprises theamino acid sequence of SEQ ID NO:116 with 4 or fewer conservative aminoacid substitutions therein. In yet another embodiment, a HCVR comprisesthe amino acid sequence of SEQ ID NO:116 with 2 or 1 conservative aminoacid substitution(s) therein. In one embodiment, a LCVR comprises theamino acid sequence of SEQ ID NO:118 with 10 or fewer conservative aminoacid substitutions therein. In another embodiment, a LCVR comprises theamino acid sequence of SEQ ID NO:118 with 8 or fewer conservative aminoacid substitutions therein. In another embodiment, a LCVR comprises theamino acid sequence of SEQ ID NO:118 with 6 or fewer conservative aminoacid substitutions therein. In another embodiment, a LCVR comprises theamino acid sequence of SEQ ID NO:118 with 4 or fewer conservative aminoacid substitutions therein. In yet another embodiment, a LCVR comprisesthe amino acid sequence of SEQ ID NO:118 with 2 or 1 conservative aminoacid substitution(s) therein.

A “neutralizing” or “blocking” antibody, is intended to refer to anantibody whose binding to Dll4 results in inhibition of the biologicalactivity of Dll4. This inhibition of the biological activity of Dll4 canbe assessed by measuring one or more indicators of Dll4 biologicalactivity. These indicators of Dll4 biological activity can be assessedby one or more of several standard in vitro or in vivo assays known inthe art. For instance, the ability of an antibody to neutralize Dll4activity is assessed by inhibition of Dll4 binding to a Notch receptor.Likewise, the term is also applicable to antibodies against othertargets, such as Notch1 and Notch4; such antibodies inhibit thebiological activities of the targets, thereby inhibiting Dll4-Notchinteractions or signal pathways.

The term “specifically binds,” or the like, means that an antibody orantigen-binding fragment thereof forms a complex with an antigen that isrelatively stable under physiologic conditions. Specific binding can becharacterized by an equilibrium dissociation constant of at least about1×10⁻⁶ M or less (e.g., a smaller K_(D) denotes a tighter binding).Methods for determining whether two molecules specifically bind are wellknown in the art and include, for example, equilibrium dialysis, surfaceplasmon resonance, and the like. An isolated antibody that specificallybinds hDll4 may, however, exhibit cross-reactivity to other antigenssuch as Dll4 molecules from other species. Moreover, multi-specificantibodies (e.g., bispecifics) that bind to hDll4 and one or moreadditional antigens are nonetheless considered antibodies that“specifically bind” hDll4, as used herein.

The term “K_(D)”, as used herein, is intended to refer to theequilibrium dissociation constant of a particular antibody-antigeninteraction.

The term “high affinity” antibody refers to those antibodies that bindDll4 with a K_(D) of about 1 nM or less, about 500 pM or less, about 400pM or less, about 300 pM or less, about 200 pM or less, or about 100 pMor less, or about 50 pM or less, as measured by surface plasmonresonance, e.g., BIACORE™ or solution-affinity ELISA.

The term “surface plasmon resonance”, as used herein, refers to anoptical phenomenon that allows for the analysis of real-time biospecificinteractions by detection of alterations in protein concentrationswithin a biosensor matrix, for example using the BIACORE™ system(Pharmacia Biosensor AB, Uppsala, Sweden and Piscataway, N.J.).

The term “epitope” is a region of an antigen that is bound by anantibody. Epitopes may be defined as structural or functional.Functional epitopes are generally a subset of the structural epitopesand have those residues that directly contribute to the affinity of theinteraction. Epitopes may also be conformational, that is, composed ofnon-linear amino acids. In certain embodiments, epitopes may includedeterminants that are chemically active surface groupings of moleculessuch as amino acids, sugar side chains, phosphoryl groups, or sulfonylgroups, and, in certain embodiments, may have specific three-dimensionalstructural characteristics, and/or specific charge characteristics. Anepitope typically includes at least 3, and more usually, at least 5 or8-10 amino acids in a unique spatial conformation.

The term “treatment” or “treat”, as used herein, is intended to meanboth prophylactic (or preventative) and therapeutic procedures, unlessotherwise indicated. Subjects in need of treatment include not onlythose who have developed a particular condition, disorder or disease,but also those who are predisposed or susceptible to developing such acondition, disorder or disease and are benefited by prophylacticprocedures so that the occurrences or recurrences, or the progression,if it occurs, of such a condition, disorder or disease are reduced,compared with those in the absence of the treatment.

By the phrase “therapeutically effective amount”, “prophylacticallyeffective amount”, or “effective amount” is meant an amount thatproduces the desired effect for which it is administered. The exactamount will depend on the purpose of the treatment, the age and the sizeof a subject treated, the route of administration, and the like, andwill be ascertainable by one skilled in the art using known techniques(see, for example, Lloyd (1999) The Art, Science and Technology ofPharmaceutical Compounding).

General Description

The present invention is based in part on the findings that the blockadeof Dll4 by a Dll4-specific antibody results in the increased number ofTreg cells, which, in turn, prevents, reduces, or delays a progressionof EAE or diabetes in mice. For a description of fully human Dll4 Ab,including recombinant human Dll4 Ab, see International PatentPublication No. WO 2008/076379.

Therapeutic Administration and Formulations

The present invention provides methods of preventing, treating orameliorating a disease or disorder in which increasing the number ofTreg cells is beneficial, comprising administering a therapeuticallyeffective amount of a pharmaceutical composition comprising a Dll4antagonist, such as a Dll4 Ab. The pharmaceutical composition comprisinga Dll4 antagonist can further comprise one or more additionaltherapeutic agents, such as immunosuppressive agents, anti-inflammatoryagents, analgesic agents, blood glucose lowering agents, and the like(see the following section). The therapeutic compositions in accordancewith the invention can be administered with suitable carriers,excipients, and other agents that are incorporated into formulations toprovide improved transfer, delivery, tolerance, and the like. Amultitude of appropriate formulations can be found in the formularyknown to all pharmaceutical chemists: Remington's PharmaceuticalSciences, Mack Publishing Company, Easton, Pa. These formulationsinclude, for example, powders, pastes, ointments, jellies, waxes, oils,lipids, lipid (cationic or anionic) containing vesicles (such asLIPOFECTIN™), DNA conjugates, anhydrous absorption pastes, oil-in-waterand water-in-oil emulsions, emulsions carbowax (polyethylene glycols ofvarious molecular weights), semi-solid gels, and semi-solid mixturescontaining carbowax. See also Powell et al. “Compendium of excipientsfor parenteral formulations” PDA (1998) J Pharm Sci Technol 52:238-311.

For systemic administration, a therapeutically effective dose can beestimated initially from in vitro assays. For example, a dose can beformulated in animal models to achieve a circulating concentration rangethat includes the IC₅₀ as determined in cell culture. Such informationcan be used to more accurately determine useful doses in humans. Initialdosages can also be estimated from in vivo data, e.g., animal models,using techniques that are well known in the art. One having ordinaryskill in the art could readily optimize administration to humans basedon animal data.

The dose may vary depending upon the age and the size (e.g., body weightor body surface area) of a subject to be administered, target disease,conditions, route of administration, and the like. For systemicadministration of Dll4 antagonists, in particular, for Dll4 antibodies,typical dosage ranges for intravenous administration are at a daily doseof about 0.01 to about 100 mg/kg of body weight, about 0.1 to about 50mg/kg, or about 0.2 to about 10 mg/kg. For subcutaneous administration,the antibodies can be administered at about 1 mg to about 800 mg, about10 mg to about 500 mg, about 20 mg to about 400 mg, about 30 mg to about300 mg, or about 50 mg to about 200 mg, at the antibody concentrationof, at least, about 25 mg/ml, about 50 mg/ml, about 75 mg/ml, about 100mg/ml, about 125 mg/ml, about 150 mg/ml, about 175 mg/ml, about 200mg/ml, or about 250 mg/ml, at least, 1 to 5 times per day, 1 to 5 timesper week, or 1 to 5 times per month. Alternatively, the antibodies canbe initially administered via intravenous injection, followed bysequential subcutaneous administration.

Various delivery systems are known and can be used to administer thepharmaceutical composition of the invention, e.g., encapsulation inliposomes, microparticles, microcapsules, recombinant cells capable ofexpressing the mutant viruses, receptor mediated endocytosis (see, e.g.,Wu et al. (1987) J. Biol. Chem. 262:4429-4432). Methods of introductioninclude, but are not limited to, intradermal, intramuscular,intraperitoneal, intravenous, subcutaneous, intranasal, epidural, andoral routes. The composition may be administered by any convenientroute, for example by infusion or bolus injection, by absorption throughepithelial or mucocutaneous linings (e.g., oral mucosa, rectal andintestinal mucosa, etc.) and may be administered together with otherbiologically active agents. Administration can be systemic or local.

The pharmaceutical composition can be also delivered in a vesicle, inparticular a liposome (see Langer (1990) Science 249:1527-1533; Treat etal. (1989) in Liposomes in the Therapy of Infectious Disease and Cancer,Lopez Berestein and Fidler (eds.), Liss, New York, pp. 353-365;Lopez-Berestein, ibid., pp. 317-327; see generally ibid.).

In certain situations, the pharmaceutical composition can be deliveredin a controlled release system. In one embodiment, a pump may be used(see Langer, supra; Sefton (1987) CRC Crit. Ref. Biomed. Eng. 14:201).In another embodiment, polymeric materials can be used; see, MedicalApplications of Controlled Release, Langer and Wise (eds.), CRC Pres.,Boca Raton, Fla. (1974). In yet another embodiment, a controlled releasesystem can be placed in proximity of the composition's target, thusrequiring only a fraction of the systemic dose (see, e.g., Goodson, inMedical Applications of Controlled Release, supra, vol. 2, pp. 115-138,1984).

The injectable preparations may include dosage forms for intravenous,subcutaneous, intracutaneous and intramuscular injections, dripinfusions, etc. These injectable preparations may be prepared by methodspublicly known. For example, the injectable preparations may beprepared, e.g., by dissolving, suspending or emulsifying the antibody orits salt described above in a sterile aqueous medium or an oily mediumconventionally used for injections. As the aqueous medium forinjections, there are, for example, physiological saline, an isotonicsolution containing glucose and other auxiliary agents, etc., which maybe used in combination with an appropriate solubilizing agent such as analcohol (e.g., ethanol), a polyalcohol (e.g., propylene glycol,polyethylene glycol), a nonionic surfactant [e.g., polysorbate 80,HCO-50 (polyoxyethylene (50 mol) adduct of hydrogenated castor oil)],etc. As the oily medium, there are employed, e.g., sesame oil, soybeanoil, etc., which may be used in combination with a solubilizing agentsuch as benzyl benzoate, benzyl alcohol, etc. The injection thusprepared is preferably filled in an appropriate ampoule. Apharmaceutical composition of the present invention can be deliveredsubcutaneously or intravenously with a standard needle and syringe. Inaddition, with respect to subcutaneous delivery, a pen delivery devicereadily has applications in delivering a pharmaceutical composition ofthe present invention. Such a pen delivery device can be reusable ordisposable. A reusable pen delivery device generally utilizes areplaceable cartridge that contains a pharmaceutical composition. Onceall of the pharmaceutical composition within the cartridge has beenadministered and the cartridge is empty, the empty cartridge can readilybe discarded and replaced with a new cartridge that contains thepharmaceutical composition. The pen delivery device can then be reused.In a disposable pen delivery device, there is no replaceable cartridge.Rather, the disposable pen delivery device comes prefilled with thepharmaceutical composition held in a reservoir within the device. Oncethe reservoir is emptied of the pharmaceutical composition, the entiredevice is discarded.

Numerous reusable pen and autoinjector delivery devices haveapplications in the subcutaneous delivery of a pharmaceuticalcomposition of the present invention. Examples include, but certainlyare not limited to AUTOPEN™ (Owen Mumford, Inc., Woodstock, UK),DISETRONIC™ pen (Disetronic Medical Systems, Burghdorf, Switzerland),HUMALOG MIX 75/25™ pen, HUMALOG™ pen, HUMALIN 70/30™ pen (Eli Lilly andCo., Indianapolis, Ind.), NOVOPEN™ I, II and III (Novo Nordisk,Copenhagen, Denmark), NOVOPEN JUNIOR™ (Novo Nordisk, Copenhagen,Denmark), BD™ pen (Becton Dickinson, Franklin Lakes, N.J.), OPTIPENT™,OPTIPEN PRO™, OPTIPEN STARLET™, and OPTICLIK™ (sanofi-aventis,Frankfurt, Germany), to name only a few. Examples of disposable pendelivery devices having applications in subcutaneous delivery of apharmaceutical composition of the present invention include, butcertainly are not limited to the SOLOSTAR™ pen (sanofi-aventis), theFLEXPEN™ (Novo Nordisk), and the KWIKPEN™ (Eli Lilly).

Advantageously, the pharmaceutical compositions for oral or parenteraluse described above are prepared into dosage forms in a unit dose suitedto fit a dose of the active ingredients. Such dosage forms in a unitdose include, for example, tablets, pills, capsules, injections(ampoules), suppositories, etc. The amount of the Dll4 antagonist, suchas a Dll4 antibody, contained is generally about 0.1 to about 800 mg perdosage form in a unit dose; especially in the form of injection, it ispreferred that the antibody is contained in about 5 to about 100 mg andin about 10 to about 250 mg for the other dosage forms.

In a certain embodiment, it may be desirable to administer thepharmaceutical compositions of the invention locally to the area in needof treatment; this may be achieved, for example, and not by way oflimitation, by local infusion during surgery, topical application, e.g.,by injection, by means of a catheter, or by means of an implant, theimplant being of a porous, non-porous, or gelatinous material, includingmembranes, such as sialastic membranes, fibers, or commercial skinsubstitutes.

Combination Therapies

In the therapeutic methods of the invention, a Dll4 antagonist may beprovided alone or in combination with one or more additional therapeuticagents, such as immunosuppressive agents or immunosuppressants,anti-inflammatory agents, analgesic agents, direct or indirect bloodglucose lowering agents, and the like. Suitable immunosuppressantsinclude, but are not limited to, glucocorticoids, cyclosporin,methotrexate, interferon β (IFN-β), tacrolimus, sirolimus, azathioprine,mercaptopurine, opioids, mycophenolate, TNF-binding proteins, such asinfliximab, eternacept, adalimumab, and the like, cytotoxic antibiotics,such as dactinomycin, anthracyclines, mitomycin C, bleomycin,mithramycin, and the like, antibodies targeting immune cells, such asanti-CD20 antibodies, anti-CD3 antibodies, and the like. Suitableanti-inflammatory agents and/or analgesics for combination therapieswith anti-Dll4 antagonists include, corticosteroids, non-steroidalanti-inflammatory drugs (NSAIDs), such as aspirin, ibuprofen, naproxenand the like, TNF-α antagonists (e.g., Infliximab or REMICADE® byCentocor Inc.; golimumab by Centocor Inc.; etanercept or ENBREL® byAmgen/Wyeth; adalimumab or HUMIRA® by Abbott Laboratories, and thelike), IL-1 antagonists (e.g., IL-1-binding fusion proteins, forexample, ARCALYST® by Regeneron Pharmaceuticals, Inc., see U.S. Pat. No.6,927,044; KINERET® by Amgen, and the like), IL-6 antagonists (e.g.,anti-IL-6 receptor antibodies as disclosed in U.S. Pat. No. 7,582,298,and ACTEMRA® by Roche), acetaminophen, morphinomimetics, and the like.Suitable glucose lowering agents include, but are not limited to,insulin and analogs thereof, biguanides, sulfonamides and ureaderivatives thereof, alpha-glucosidase inhibitors, thiazolidinedione andderivatives thereof, dipeptidyl peptidase-4 inhibitors, guar gum,repaglinide, nateglinide, exenatide, pramlintide, benfluorex,liraglutide, mitiglinide, aldose reductase inhibitors, and the like.

The Dll4 antagonist, such as hDll4 Ab or fragment thereof, and theadditional therapeutic agent(s) described above can be co-administeredtogether or separately. Where separate dosage formulations are used, theantibody or fragment thereof of the invention and the additional agentscan be administered concurrently, or separately at staggered times,i.e., sequentially, in appropriate orders.

Kits

The invention further provides an article of manufacturing or kit,comprising a packaging material, container and a pharmaceutical agentcontained within the container, wherein the pharmaceutical agentcomprises at least one Dll4 antagonist, such as Dll4 antibody, and atleast one additional therapeutic agent, and wherein the packagingmaterial comprises a label or package insert showing indications anddirections for use. In one embodiment, the Dll4 antagonist and theadditional therapeutic agent may be contained in separate containers.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how tomake and use the methods and compositions of the invention, and are notintended to limit the scope of what the inventors regard as theirinvention. Efforts have been made to ensure accuracy with respect tonumbers used (e.g., amounts, temperature, etc.), but some experimentalerrors and deviations should be accounted for. Unless indicatedotherwise, parts are parts by weight, temperature is in degreesCentigrade, pressure is at or near atmospheric, and figure errorbars=mean±SEM.

In the examples below, the following antibodies in Dulbecco's PBS(GIBCO® INVITROGEN™) 1× supplemented with 3% FCS, were used to staincells for flow cytometry purpose: For DCs, antibodies againstsignal-regulatory protein a (Sirp-α; cat# P84; BD Biosciences), B220(cat# RA3-6B2), PDCA-1 (cat# eBio927), CD8 (cat#53-6.7), CD11b (cat#M1/70), MHCII (cat# M5/114.15.2), CD11c (cat# N418), and CD135 (cat#A2F10), respectively; for T, B and NK cells, antibodies against CD4(cat# GK1.5 or L3T4), CD3 (cat#145-2C11), CD25 (cat# PC61 or 7D4), CD44(cat# IM7), FoxP3 (cat# FJK16s); and F4/80 (cat# BM8), NK1.1 (cat#PK136), IgM (cat# II/41), IgD (cat#26-11c), CD43 (cat# S7), CD21 (cat#eBio4E3), HSA (cat# M1/69), and CD23 (cat# B3B4), respectively, (allfrom eBioscience).

Example 1 Effect of Dll4 Blockade on Development of B Cells, DendriticCells and T Cells

It has been shown that Dll4-Notch1 inhibition leads to a complete blockin T cell development accompanied by ectopic appearance of B cells andan expansion of dendritic cells (DC) that can arise from Pro-T cell toDC fate conversion within the thymus (Hozumi et al. 2008, J Exp Med205(11):2507-2513; Koch et al., 2008, J Exp Med 205(11):2515-2523; andFeyerabend et al. 2009, Immunity 30:1-13). It is, however, still unknownas to which specific stage of DC development is directly affected by theDll4 blockade.

To answer this question, 6 week-old C57B1/6 mice (Jackson Labs) wereinjected subcutaneously with 5 or 25 mg/kg of anti-Dll4 Ab (REGN577)(n=5) or human Fc fragment (control) (n=5), twice a week for two weeks.REGN577 was prepared in-house based on the published sequence (WO2007/143689). REGN 577 binds to human and mouse Dll4, but does notdetectably binds human Dll1 and JAG1. Fourteen (14) days after theinjection, thymi and spleens were harvested and digested at 37° C. for30 min in complete RPMI 1640 medium (Invitrogen) supplemented with 10%fetal calf serum (FCS) and containing Collagenase D (Sigma Aldrich). Tostop the reaction, 2 mM EDTA was added and the organ suspension waspassed through a 70-mm cell strainer. Bone marrow (BM) was collectedfrom each mouse by flushing femurs and tibias in complete RPMI 1640medium supplemented with 10% FCS and cells were resuspended in RPMImedium. T cell, B cell and DC subsets were evaluated by flow cytometryafter the cells were stained with the antibodies against specificmarkers described above. The stained cells were run on a BD™ LSR II FlowCytometer (BD Biosciences) and the data were analyzed using FlowJosoftware (version 8.8.6; Tree Star Inc.).

FIGS. 1A and 1B show the T and B cell populations in the thymus. Asshown in FIG. 1A, Dll4 blockade induced a significant increase in thenumber of double negative (“DN”; CD4⁻CD8⁻) T cells and a decrease in thenumber of double positive (“DP”; CD4⁺CD8⁺) T cells within the thymus. Inaddition, the same treatment induced an ectopic appearance of B cellswithin the thymus, which arose from Pro-T cells (La, CD44⁺CD25⁻CD4⁻CD8⁻cells at DN1 stage) (see FIG. 1B). In contrast, Dll4 blockade had noeffect on B cell development in the bone marrow (FIG. 2A) or in theperipheral splenic B cell subpopulations (FIG. 2B). Furthermore, Dll4blockade induced expansion of conventional DCs (“cDCs”; B220⁻CD11c⁺) andplasmacytoid DCs (“pDCs”; PDCA1⁺B220⁺CD11C⁺) in the thymus (FIG. 3A),with significant expansion starting at day 7 (p<0.001) through day 14(p<0.001) and continued through day 21 (p<0.01) (FIG. 3B) after theinitial injection of Dll4 Ab. Numbers in dot plots of FIG. 3A representaverage percentages of DCs among total cells at day 14. Further, DCswere expanded in the periphery of mice treated with Dll4 Ab (REGN577).Fold increases in percentage and absolute number of DCs in spleen upontreatment with Dll4 Ab, compared to the control mice (hFc-treated), areshown in Table 1.

TABLE 1 Days after Fold-increase Fold-increase initial injection inpercentage in absolute number 3 1.0 1.0 7 1.1 1.1 14 1.6 2.0 21 1.3 1.7

It is known that lymphoid tissue cDCs, pDCs and monocytes share a commonprogenitor called “macrophage and DC precursor” or “MDP”, which can beidentified by its surface phenotype “Lin⁻cKit^(hi)CD115⁺FLT3⁺”, while adistinct progenitor called “common DC precursor” or “CDP” with“Lin⁻cKit^(lo)CD115⁺FLT3⁺” is restricted to producing cDCs and pDCs.Although monocytes can develop many of the phenotypic features of DCsunder inflammatory conditions, the cDC, pDC and monocytes lineagesseparate by the time they reach tissues, and neither monocytes nor pDCsdevelop into cDCs under steady state conditions. Unlike monocytes andpDCs, cDCs in lymphoid tissue are thought to emerge from the bone marrowas immature cells that must further differentiate and divide in lymphoidorgans. Pre-DCs (MHCII^(lo)CD11c^(int)CD135⁺Sirp-α^(int)) and latepre-DCs (MHCII^(lo)CD11c^(int)), are precursors primarily to cDCs thatarise in bone marrow (Liu et al., 2009, Science 324:392-397).

To identify any effect of Dll4 Ab on DC progenitor homeostasis, thelevels of MDP and CDP in the thymus, the bone marrow and the spleen wereevaluated by flow cytometry. MDP and CDP were only detected in the bonemarrow, but neither in the thymus nor in the spleen (data not shown).Furthermore, Dll4 blockade did not induce expansion of early progenitorsin bone marrow compared to the control-treated mice. Thus, the resultsuggested that the Dll4 Ab could act at a later stage, i.e., pre-DCstage, of DC development than MDP and CDP.

Accordingly, pre-DCs and late pre-DCs in the thymus and the bone marrowwere searched for using the flow cytometry. As shown in FIG. 3C,MHCII^(lo)CD11c^(int) DCs, which are normally present in the bonemarrow, were only expanded in the thymus 14 days after the Dll4 Abtreatment (p<0.001), while no expansion of MHCII^(lo)CD11c^(int) DCs wasdetected in the BM of the same mice (data not shown). Thus, the DCexpansion originated from the pre-DC stage was restricted to thymus. Toevaluate the origin of MHCII^(lo)CD11c^(int) DCs in the thymus, flowcytometry was conducted to identify MHCII^(lo)CD11c^(int) DCs in the DN1(CD4⁻CD8⁻CD44⁺CD25⁻) pro-T cell population. As shown in FIG. 3D,MHCII^(lo)CD11c^(int) DCs were detected within the DN1 pro-T cellpopulation upon Dll4 blockade at day 3. No MHCII^(lo)CD11c^(int) DCswere detected in the absence of Dll4 Ab treatment as well as within DN2,DN3 and DN4 T cell populations upon Dll4 Ab treatment (data not shown).No change in peripheral DC homeostasis was observed upon Dll4 Abtreatment (data not shown). Thus, Dll4 blockade induced a significantexpansion of MHCII^(lo)CD11^(int) DCs within DN1 pro-T cell populationin the thymus at day 3 (p<0.01) (FIG. 3D) with a peak of expansion atday 14 (p<0.001) (data not shown). Meanwhile, mature DC subsets expandedat day 7 (p<0.001) through day 21 (p<0.01) in the thymus, as discussedabove (see FIG. 3B).

To examine whether DC expansion could originate from uncommitted T-cellprecursors, DN1 CD45.1⁺Lin⁻ sorted cells were intra-thymicallytransferred into CD45.2⁺ host mice treated with anti-Dll4 Ab. It wasfound that CD45.1⁺ cells were accumulated in DN1 stage (data not shown)and immature DCs (imDCs) were detected and expanded in thymus (FIG. 4)(p<0.01). No cells were detected in the control Ab-treated mice,possibly because most of DN1-transferred cells were eliminated by T cellnegative selection. It was concluded that Dll4 blockade promotes thedevelopment of intra-thymic alternative DC lineage originating from acommon T/DC DN1 progenitor.

Fms-like tyrosine kinase 3 ligand (Flt3-L) is sufficient and essentialfor the differentiation of bone marrow progenitors into DCs and thedevelopment of peripheral DCs. Serum levels of Flt3-L were unchanged inanti-Dll4 Ab-treated WT animals (data not shown). Furthermore, as shownin Tables 2 and 3 below, the percentages of DC in thymus were expandedin wild-type mice (WT) (Tables 2 and 3), FLt3-L knock-out mice(Flt3-L^(−/−)) (p<0.05) (Table 2), and Flt3-R knock-out mice(Flt3-R^(−/−)) (p<0.001) (Table 3), all treated with Dll4 Ab, comparedto those treated with control Ab. Thus, Dll4 blockade induces aFlt3-independent DC expansion in thymus.

TABLE 2 % DC in Thymus in Mice Treated with: Mice Control Ab DII4 Ab WT0.04 ± 0.005 0.58 ± 0.13 Flt3-L^(−/−) 0.04 ± 0.006 0.45 ± 0.13

TABLE 3 % DC in Thymus of Mice Treated with: Mice Control Ab DII4 Ab WT 0.03 ± 0.003 0.37 ± 0.03 Flt3-R^(−/−) 0.06 ± 0.01 0.44 ± 0.02

The ability of early T cell progenitors to re-derive towards a non-Tcell phenotype has been observed (James P. Di Santo, 2010, Science329:44-45). Gene array analysis was performed in thymocytes and pro-Tcells to determine the effect of anti-Dll4 Ab treatment in genesimplicated in T versus B and DC cell-lineage specification. It was foundthat the genes essential for T cell commitment (e.g., Tcf7, Gata3, andEts1) were downregulated, while genes (Lyl1, Sfpi1) that can each blockT cell development, were up-regulated (data not shown; see Di Santo,2010, supra). Most interestingly, genes controlling DC (PU.1 and Spi-B)and B cell development were also up-regulated (data not shown; see M.Merad et al. 2009, Blood 113:3418-3427). In addition, expression of RelBand Id2 as well as interferon regulatory factors (IRFs) 2, 4 and 8-keytranscription factors involved in DC subset development were increased(data not shown; see Merad et al. 2009, supra). Finally, gene expressionof CSF-1 (M-CSF), a key cytokine involved in DCs development, was foundto be up-regulated upon anti-Dll4 Ab treatment (p<0.05; data not shown).Furthermore, CSF-1 serum levels were increased upon anti-Dll4 Abtreatment (FIG. 5; p<0.05) (see B. Francke, et al. 2008, Blood111:150-159). Thus, it can be concluded that Dll4-Notch signalingblockade down-regulates transcription factors specific for T celllineage commitment, while up-regulating others crucial in DCdevelopment.

Example 2 Effect of Dll4 Deletion on T Cell Development

To evaluate if the effect of Dll4 on DC development observed in Example1 above was intrinsic to Dll4, DLL4COIN mice, in which Dll4 isconditionally inactivated, were prepared. “Conditional-by-inversion(COIN)” alleles are conditional alleles that rely on an inversibleelement (“COIN element”) to provide recombinase-mediated conditionalmutations. DLL4COIN mice contain a tamoxifen-inducible Cre recombinaseconstruct, CreERT2, which encodes a Cre recombinase fused to a mutantestrogen ligand-binding domain (ERT2). CreERT2 is essentially inactivein the absence of tamoxifen and is also not activated by endogenousestrogens. Tamoxifen treatment of the mice will activate CreERT2 andcause the inversion of the COIN element, which abrogates thetranscription of all exons downstream of the COIN insertion point,thereby knocking out Dll4. For details of CreERT2 recombinase system,see Feil et al. 1997, Biochemical and Biophysical ResearchCommunications 237:752-757.

DLL4COIN mice (n=6) were injected intraperitoneally (i.p.) withtamoxifen (TAM) (cat# T-5648, Sigma) at 3 mg/150 μl corn oil per mousethree (3) times per week for 2 weeks. DLL4COIN control mice (n=6) weregiven corn oil without tamoxifen. Likewise, wild type C5B1/6 mice weretreated with tamoxifen (n=6) or corn oil only (n=6). Mice were monitoredfor signs of distress (e.g., fur appearance, low activity, etc.),infections, and excessive loss of body weight. Mice were weighedapproximately three times per week. Any mouse that lost more than 20%body weight was removed from the experiment. After 2 weeks of thetreatment, thymi were harvested and the thymic cells were analyzed byflow cytometry.

As shown in FIG. 6, in the absence of Dll4 (i.e., in tamoxifen-treatedmice), B cells and both pDCs and cDCs were expanded in the thymus,compared to the corn oil-treated mice, indicating that the effects ofDll4 on DC development and homeostasis observed in Example 1 were indeedintrinsic to Dll4. Thus, Dll4-Notch signaling seems to sustain T cellcommitment by suppressing non-T cell lineage potential within the pro-Tcell population.

Example 3 Effect of Dll4 Blockade or Dll4 Deletion on Tregs Homeostasis

It has been recently shown that Tregs are essential for maintainingnormal number of DCs. Upon Treg depletion there is a compensatoryFms-like tyrosine kinase 3 (Flt3)-dependent increase of DCs (Liu et al.,2009, supra). Furthermore, two independent groups showed a feedbackcontrol of regulatory T cell homeostasis by DCs in vivo; i.e.,increasing the numbers of DCs leads to an increased Treg division andaccumulation, which could prevent autoimmune disease development(Darrasse-Jeze G. et al., 2009, J. Exp. Med. 206(9):1853-1862; and SweeL K et al., 2009, Blood 113(25):6277-6287).

To determine if Dll4 blockade could affect Treg homeostasis, Tregnumbers in thymi of the mice treated with the Dll4 Ab or human Fc(control) in Example 1 were measured by flow cytometry. As shown in FIG.7A, Dll4 blockade resulted in a robust expansion of Tregs within thethymus at day 14 after the initial injection. The expansion of Tregsstarted at day 7 (p<0.001) and reached a maximum effect at day 14 in thethymus (p<0.001) after the initial injection (see FIG. 7B), while in theperiphery (i.e., spleen) Tregs started appearing only between 14 and 21days (p<0.05) (FIG. 7B and Table 4). In Table 4, fold increases inpercentage and absolute number of Tregs in spleen upon treatment withDll4 Ab, compared to the control mice (hFc-treated), are shown.

TABLE 4 Days after Fold-increase Fold-increase initial injection inpercentage in absolute number 3 1.0 1.0 7 1.0 1.2 14 1.1 1.7 21 1.1 1.2

To evaluate if the observed Treg expansion was intrinsic to Dll4molecule, Treg numbers in thymi of DLL4COIN mice from Example 2 werealso measured by flow cytometry. As observed with the Dll4 blockade byDll4 Ab, conditional inactivation of Dll4 by tamoxifen treatment alsoresulted in the expansion of Tregs in the thymus, compared to thecorn-oil treated mice (see FIG. 7C) as well as wild-type mice treatedwith tamoxifen (data not shown). Thus, Dll4-Notch signaling sustains DCsand consequently Treg homeostasis and T cell commitment.

A similar experiment was conducted in mice expressing human Dll4(“humanized Dll4 mice”) using anti-Dll4 Ab (REGN421 having HCVR and LCVRsequences of SEQ ID NO:116 and 118, respectively), which is known tobind an N-terminal-DSL domain of human Dll4. The humanized Dll4 mousewas prepared by replacing the entire extracellular domain of the mouseDll4 gene with the corresponding extracellular region of the human Dll4gene (7 kb) in embryonic stem (ES) cells of F1 C57BL/6/129. HomozygoushDll4 mice were generated and bred into C57BL/6 background. HumanizedDll4 mice were treated with 5 mg/kg of hFc (control; n=6), or 1 mg/kg(n=6) or 5 mg/kg (n=6) of REGN421 Ab twice per week for two weeks. Twomice from each treatment group were sacrificed at day 7 and 2 more miceper group were sacrificed at day 14. The thymi were harvested and thecells were stained and examined by flow cytometry. The remaining micewere allowed to recover for additional 4 weeks without any treatmentand, at day 28 after the cessation of treatment, they were sacrificedand the thymic cells were analyzed using flow cytometry. After two weeksof treatment, an increase of cDC and pDCs (FIG. 8A) as well as asignificant increase in Treg population (FIG. 8B) was observed in thethymus of the anti-Dll4 Ab-treated mice (p<0.01). In the thymi of themice that received Dll4 Ab for 2 weeks, followed by 4 weeks ofnon-treatment, both DC and Treg numbers returned to the normal level atthe end of the period (FIGS. 8A and 8B). Meanwhile, an expansion of DCsand Tregs was also observed in the periphery of Dll4-Ab treated mice,compared to hFc treated mice (data not shown).

Example 4 Effect of Notch Receptor Blockade on Tregs

It has been shown that an expansion of DCs is leading to an expansion ofTregs (Darrasse-Jeze G. et al. 2009). As discussed above, it wasobserved that upon Dll4 blockade both DCs and Tregs were expanded in thethymus (FIG. 3A and FIG. 7A). In addition, an expansion of bothpercentages and absolute numbers of DCs and Tregs was also found in theperiphery of Dll4-Ab treated mice (Tables 1 and 4). In order todetermine if blockade of Notch receptors would lead to the samephenotype as Dll4 deletion, Nicastrin knockout (KO) mice (Nic^(−/−))were studied. Nicastrin is a molecule involved in the Notch signalingpathway and genetic ablation of nicastrin in nicastrin deficient miceresults in a blockade of signal transduction downstream of Notchreceptors 1, 2, 3 and 4 (Aifantis et al. un-published data). NicastrinKO mice were shown to exhibit similar phenotype as theDll4-deleted/blocked mice with an increased number of Tregs, both inpercentage and in absolute number, in thymus as well as in spleen (seeTable 5).

TABLE 5 Thymus Spleen Nicastrin Nicastrin KO Treg Control mice KO miceControl mice mice Treg (%) in 3.3 ± 0.2 15.2 ± 2.0 16.0 ± 1.3  33.9 ±2.1  CD3⁺CD4⁺ (p < 0.1) (p < 0.0001) cells Ratio of  0.04 ± 0.002  0.2 ±0.03 0.2 ± 0.01 0.6 ± 0.06 absolute (p < 0.01) (p < 0.0001) numbers(Treg/Teff)

Finally, when bone marrow cells (BM) from Nic^(−/−) mice weretransferred into lethally irradiated WT mice, the expansion of thymicTregs was observed in Nic^(−/−)→WT chimeras, suggesting that such anexpansion was a cell-autonomous effect; and Dll4 blockade of therecipient mice with anti-Dll4 Ab had no additive effect (see Table 6).

TABLE 6 % Treg in CD3⁺CD4⁺ Cells in Recipient WT Mice Treated with: BMDonors Control Ab Anti-DII4 Ab WT 3.6 ± 0.4 35 ± 4 Nic^(−/−) 37 ± 2  41± 2

These results suggest that interruption of Dll4-Notch signaling byblocking either Dll4 or Notch receptors leads to similar phenotypes withregard to the expansion of Tregs.

To determine if the expansion of Tregs upon Dll4 blockade correlateswith DC numbers (Darrasse-Jeze G. et al. 2009, supra), mice lacking DCswere prepared and tested with the Dll4 Ab as in Example 1. Transgenicmice expressing primate diphtheria toxin receptor (DTR) are conferredwith diphtheria toxin (DT) sensitivity to their cells, which areDT-insensitive otherwise. DT enters the cells via interaction of its Bsubunit with the cellular DTR and, upon endocytosis, the DT A subunit isreleased and catalyzes ADP-ribosylation of elongation factor 2,resulting in the inhibition of protein synthesis followed by rapidapoptosis in both mitotic and terminally differentiated cells.Specificity and timing of cell ablation can be determined by celltype-restricted promoter/enhancer elements and by the regimen of thetoxin administration, respectively. To target DT sensitivity to DC, Junget al. (2002, Immunity 17:211-220) have generated mice (CD11cre-DTRmice) that carry a transgene encoding a simian DTR-GFP (greenfluorescent protein) fusion protein under the control of the murineCD11c promoter. Since CD11c encodes for all DCs, all murine DC subsetsexpressing CD11c are deleted upon administration of DT.

Thus-prepared transgenic mice lacking DCs were treated with the Dll4 Abor hFc control according to the protocol described in Example 1.Fourteen (14) days after the treatment, thymi and spleens were harvestedand prepared for analysis. The expression level of Dll4 on the surfacesof specific DC or T cell subsets was evaluated by flow cytometry inorder to determine which specific subset the Dll4 Ab bound to. Theresults showed that DCs and T cells did not express detectable levels ofDll4 on their surface (data not shown). This observation is corroboratedby the report that Dll4 is expressed on the surface of thymic epithelialcells (TECs) (Koch et al. 2008, supra). Most importantly, however, itwas found that the Dll4 Ab treatment of mice lacking DCs was not able toinduce expansion of Treg, while wild-type mice (i.e., DC non-deletedmice) treated with Dll4 Ab significantly increased the proportion ofTregs among CD3⁺CD4⁺ cells (p<0.001), suggesting that the expansion ofTregs upon Dll4 Ab treatment was at least in part mediated via DCexpansion.

Example 5 Effect of Dll4 Blockade in Experimental AutoimmuneEncephalomyelitis (EAE)

CD4⁺CD25⁺FoxP3⁺ natural regulatory T cells (i.e., Tregs) play animportant role in maintaining self-tolerance and suppress auto-immunediseases, such as type 1 diabetes, autoimmune encephalomyelitis, GVHDand inflammatory bowel disease (IBD) (Darrasse-Jeze G. et al. 2009,supra; Swee L K et al. 2009, supra; and McGreachy et al., 2005,175(5):3025-3032).

To see if the increased number of Tregs resulted from Dll4 blockadewould prevent autoimmune diseases, the impact of Dll4 blockade on an EAEwas studied in a mouse model. The EAE mouse model was established byinjecting in the footpad of C57B1/6 mice with myelin oligodendrocyteglycoprotein (MOG) peptide emulsified in complete Freund adjuvant (CFA)followed (24 hours later) by Pertussis toxin (PTX) injection to inducedisease. The disease score was determined based on the followingsymptoms: (0) no symptoms; (1) limp tail; (2) limp tail with hind-legweakness; (3) partial hind-leg paralysis; (4) complete hind-legparalysis; (5) paralysis of all limbs; and (6) moribund. Twelve totwenty-four hours prior to the immunization, mice in a pre-inductiongroup (n=10) also received a subcutaneous injection of 25 mg/kg ofeither anti-Dll4 Ab (REGN577) or isotype control Ab (human antibodyspecific for CD20, prepared in-house according to the disclosure in US2008/0260641), or PS/2 (rat/mouse IgG2b against murine integrin-likecellular adhesion molecule VLA-4; ATCC #CRL-1911), while mice in apost-induction group (n=10) received the same on the day the symptomsappeared. PS/2 Ab is known to exacerbate disease relapses and increasethe accumulation of CD4⁺ T cells in the central nervous system in amouse model for relapsing experimental autoimmune encephalomyelitis(R-EAE) (Theien B E et al., 2001, J Clin Invest 107(8):995-1006). Theinjections of antibodies were conducted twice a week, for two weeks. Atthe conclusion of the experiment, spinal cords of the mice werecarefully removed, crushed and then incubated in a RPMI 1640 mediumcontaining Collagenase D (Sigma Aldrich). EDTA at 2 mM was added to stopthe reaction and the mixture was passed through a 70-mm cell strainerand the cell content was analyzed by flow cytometry.

As shown in FIGS. 9A and 9B, the mice treated with isotype control Abdeveloped symptoms (i.e., having disease scores more than “0”) startingaround 10-14 days and peaking between 15 and 21 days, after the MOGinjections. In contrast, mice treated with Dll4 Ab were fully preventedfrom disease progression compared to mice treated with control Ab. Table7 shows fold-increases in percentage and in absolute number of Tregs inthymus and spleen of the mice treated with Dll4 Ab, compared to micetreated with control Ab.

TABLE 7 Treg in Thymus Treg in Spleen Days Fold- Fold-increase Fold-Fold-increase after MOG increase in absolute in increase in in absoluteinjection percentage number percentage number 12 2.46 0.77 1.08 1.46 184.88 2.67 1.23 1.89 21 1.41 1.01 1.85 4.77

Tregs seemed to expand primarily within the thymus at around day 18 anda significant expansion was seen in periphery (i.e., spleen) only afterday 21.

Under this particular experimental condition, Dll4 Ab treatment at thepost-induction stage did not show significant improvement in diseaseprogression. Dosages and/or frequency of Dll4 Ab administrations can befurther adjusted within the knowledge of one skilled in the art.Importantly, however, the mice that had received pre-induction Dll4 Abexhibited a significant decrease in cell infiltration into the spine atday 18, compared to those that had received control Ab (see Table 8below). Cell infiltration observed in the spinal cord of the micetreated with control Ab could be a major contributor to the diseaseprocess in those mice.

As shown in Table 8, there was a 8-fold decrease (p<0.0001) inmacrophages (F4/80⁺), a 2.7-fold decrease (p<0.0001) in NK cells,1.7-fold decrease (p<0.001) in CD11b cells, and 2.5-fold decrease(p<0.001) in B cells in spinal cord of mice treated with Dll4 Ab,compared to the spinal cord of mice treated with control Ab at day 21.

TABLE 8 Absolute Number of Infiltrating Cells in Spine (×10⁶) CD11b⁺Days Macrophages NK cells B cells myeloid cells after MOG DII4 DII4 DII4DII4 injection Control Ab Control Ab Control Ab Control Ab 12  0.4 ±0.05 0.3 ± 0.01 0.2 ± 0.03 0.1 ± 0.004  0.3 ± 0.005  0.2 ± 0.006  0.9 ±0.09  0.6 ± 0.02 18 1.7 ± 0.5 0.2 ± 0.02 0.2 ± 0.06 0.1 ± 0.005 1.8 ±0.2 1.0 ± 0.08 4.7 ± 0.7 1.8 ± 0.1 21 1.6 ± 0.1 0.2 ± 0.01 0.8 ± 0.070.3 ± 0.03  1.5 ± 0.1 0.6 ± 0.02 4.8 ± 0.1 2.9 ± 0.2

Furthermore, production of IL-17 and IFN-γ in lymph nodes in the micetreated with Dll4 Ab was significantly diminished (p<0.001) (FIG. 10).Thus, Dll4 could be involved in the pathogenesis of EAE by mediating Th1development and Dll4 Ab treatment can prevent disease induction byblocking the secretion of Th1 and Th17 cytokines.

Example 6 Effect of Dll4 Blockade on Diabetes

The effect of Dll4 blockade on diabetes was also tested in NOD/ShiLtJmice (“NOD mice”), a polygenic model for type 1 diabetes (Makino S etal., 1980, Jikken Dobutsu 29 (1):1-13; Serreze D V et al., 1997, JImmunol 158 (8):3978-86). Diabetes in NOD/ShiLtJ mice is characterizedby insulitis and leukocytic infiltration of the pancreatic islets.Marked decreases in pancreatic insulin content occur spontaneously infemales at about 12 weeks of age and several weeks later in males.Consequently, plasma glucose levels increase to greater than 250 mg/dL.NOD mice were checked twice a week for blood glucose levels, using aONETOUCH® mini (LifeScan, Inc.). The mice were considered diabetic aftertwo consecutive readings over 250 mg/dL of blood glucose. The onset ofdiabetes was dated from the first of the sequential diabeticmeasurements. The mice were injected with hFc (n=5) or anti-Dll4 Ab(Regn577) (n=10) 25 mg/kg twice per week for 7 weeks starting at 9 weeksof age. Blood glucose levels were monitored once a week with bloodsamples from the tail.

As shown in FIG. 11A, mice treated with hFc started developingspontaneous diabetes with blood glucose levels higher than 250 mg/dLafter 13 weeks of age (•). In contrast, mice treated with anti-Dll4 Ab(REGN577) showed no sign of increased glucose level through 25 weeks ofage (▪) and the measurements are continuing for additional 10 weeks.Dll4-Ab treatment before the diabetes onset prevented the development ofdiabetes and the treated animals did not seem to ever develop diabetes.Interestingly, when 5 out of 10 mice treated with Dll4 Ab were injectedwith anti-CD25 (PC61) mAb at 20 weeks of age in order to deplete theTregs (♦), their blood glucose levels started increasing 1-2 weeks laterand the mice became diabetic. This indicated that the preventive effectof Dll4 Ab on type I diabetes was mediated, at least in part, by Tregs(FIG. 11A).

Insulin and GAD65 are two standard auto-antibodies that are found in thesera of diabetic NOD mice as well as of diabetic individuals.Accordingly, the serum levels of auto-antibodies in the mice treatedwith hFc control or Dll4 Ab were measured by ELISA. As shown in FIG.11B, Dll4-Ab treatment blocked the production of anti-Insulin (□) andanti-GAD65 (▪) auto-antibodies at levels similar to those of untreatedWT C57Bl/6 (i.e., non-NOD mice; negative control animals). In contrast,NOD (diabetic) mice that received hFc control had high levels ofauto-antibodies in their sera. In addition, when the pancreas sectionsof 23-week old mice, which had been treated with Dll4 Ab and showing nodiabetic symptoms, were stained with H&E (Hematoxylin and Eosin), normalnumbers of pancreatic islets (the cells that produce insulin or glucagonand their destruction is directly correlated with diabetes incidence)with preserved morphology were observed (FIG. 11C, left panel, and FIG.11D, left panel). Further, no cellular infiltration within the isletswas observed with Dll4 Ab-treated mice (FIG. 11C, left panel, and FIG.11D, right panel). In contrast, diabetic animals, which had been treatedwith hFc control, had significantly lower numbers of pancreatic islets(FIG. 11C, right panel, and FIG. 11D, left panel) in their pancreas thanthe Dll4 Ab-treated mice and the remaining very few islets containedhigh levels of cellular infiltration (FIG. 11C, right panel, and FIG.11D, right panel). Thus, Dll4 Ab was able to prevent diabetes completelyfor a prolonged period and its effect seemed to be, at least in part,mediated by the expansion of Tregs; however, it is possible that anadditional mechanism(s) may be involved in the protective effect of Dll4Ab on pancreatic islets and/or insulin.

Actual blood glucose levels of the diabetic mice treated with Dll4 Abwere determined and compared with those of the mice treated with hFccontrol. Diabetic mice were treated with 25 mg/kg of Dll4 Ab (n=3) orcontrol hFc (n=4) at the onset of disease (day 0). Upon Dll4 Abtreatment, diabetic mice significantly decreased the glucose level fromabout 350 mg/dL to a normal level (about 120-130 mg/dL) (FIG. 11E). Thiseffect lasted for an average of 4 to 5 weeks. In general, it was furtherobserved that, when diabetic mice having less than 350 mg/dL of bloodglucose was treated with Dll4 Ab, their glucose levels dropped to thenormal level and this effect lasted longer than those having more than350 mg/dL of blood glucose at the time of treatment. This indicates thatthere is a certain window of opportunity for a prolonged and effectivetreatment for controlling blood glucose levels with Dll4 Ab. Thus,without being bound by any specific mechanisms described herein, theseobservations suggest that Dll4 antibodies have a great therapeuticpotential for type I diabetes.

The results from the experiments above have revealed an existence of apreviously unknown regulatory loop that controls the numbers of Tregcells and DCs in vivo. This regulatory circuit is likely to be essentialto the balance between immunity and tolerance, but most importantlymakes, for the first time, the link between three important componentsof the immune system, i.e., Dll4-DCs-Tregs. Thus, a therapy with Dll4antagonists presents an effective methodology to control Treg numbers invivo and consequently control the progression of autoimmune diseases andrelated conditions.

The invention claimed is:
 1. A method of increasing the number ofregulatory T (Treg) cells in a subject diagnosed with multiplesclerosis, comprising administering an effective amount of an anti-Dll4antibody or fragment thereof to the subject, wherein the anti-Dll4antibody or fragment thereof binds human Dll4 and blocks an interactionbetween Dll4 and a Notch receptor and the number of Treg cells isincreased.
 2. The method of claim 1, wherein the antibody or fragmentthereof comprises a heavy chain variable region (HCVR) comprising heavychain CDR1, CDR2 and CDR3 sequences of SEQ ID NO:22, 24 and 26,respectively, and a light chain variable region (LCVR) comprising lightchain CDR1, CDR2 and CDR3 sequences of SEQ ID NO:30, 32 and 34,respectively.
 3. The method of claim 2, wherein the antibody or fragmentthereof comprises (a) a HCVR sequence of SEQ ID NO:20 or 116, and a LCVRsequence of SEQ ID NO:28 or 118, or (b) a HCVR/LCVR combination of SEQID NO:20/28 or 116/118.
 4. A method of treating or ameliorating multiplesclerosis, the method comprising administering a therapeuticallyeffective amount of an anti-Dll4 antibody or fragment thereof to asubject diagnosed with multiple sclerosis, wherein the anti-Dll4antibody or fragment thereof binds to human Dll4 and blocks aninteraction between Dll4 and Notch receptor, thereby increasing thenumber of Treg cells.
 5. The method of claim 4, wherein the antibody orfragment thereof comprises a heavy chain variable region (HCVR)comprising heavy chain CDR1, CDR2 and CDR3 sequences of SEQ ID NO:22, 24and 26, respectively, and a light chain variable region (LCVR)comprising light chain CDR1, CDR2 and CDR3 sequences of SEQ ID NO:30, 32and 34, respectively.
 6. The method of claim 5, wherein the antibody orfragment thereof comprises (a) a HCVR sequence of SEQ ID NO:20 or 116,and a LCVR sequence of SEQ ID NO:28 or 118, or (b) a HCVR/LCVRcombination of SEQ ID NO:20/28 or 116/118.
 7. The method of claim 4,further comprising coadministering concurrently or sequentially with theanti-Dll4 antibody or fragment thereof a therapeutically effectiveamount of at least one additional therapeutic agent selected from thegroup consisting of immunosuppressant, anti-inflammatory agent, andanalgesic agent.
 8. The method of claim 7, wherein the additionaltherapeutic agent is at least one selected from the group consisting ofglucocorticoides, cyclosporin, methotrexate, non-steroidalanti-inflammatory drugs (NSAIDs), TNF-α antagonists, IL-1 antagonists,IL-6 antagonists, and opioids.
 9. A method of reducing recurrence ofmultiple sclerosis in a subject previously diagnosed with multiplesclerosis, comprising administering to the subject a prophylacticallyeffective amount of an anti-Dll4 antibody or fragment thereof that bindshuman Dll4 and blocks an interaction between Dll4 and a Notch receptor,thereby increasing the number of Treg cells.
 10. The method of claim 9,wherein the antibody or fragment thereof comprises a heavy chainvariable region (HCVR) comprising heavy chain CDR1, CDR2 and CDR3sequences of SEQ ID NO:22, 24 and 26, respectively, and a light chainvariable region (LCVR) comprising light chain CDR1, CDR2 and CDR3sequences of SEQ ID NO:30, 32 and 34, respectively, or both.
 11. Themethod of claim 10, wherein the antibody or fragment thereof comprises(a) a HCVR sequence of SEQ ID NO:20 or 116, and a LCVR sequence of SEQID NO:28 or 118, or (b) a HCVR/LCVR combination of SEQ ID NO:20/28 or116/118.
 12. The method of claim 9, further comprising coadministeringconcurrently or sequentially with the anti-Dll4 antibody or fragmentthereof a prophylactically effective amount of at least one additionaltherapeutic agent selected from the group consisting ofimmunosuppressant, anti-inflammatory agent, and analgesic agent.
 13. Themethod of claim 12, wherein the additional therapeutic agent is at leastone selected from the group consisting of glucocorticoides, cyclosporin,methotrexate, non-steroidal anti-inflammatory drugs (NSAIDs), TNF-αantagonists, IL-1 antagonists, IL-6 antagonists, and opioids.